word about windshields
1. I need one badly, mine (probably original) is pitted to hell and gone.
2. This subject came up on Art's CS Registry forum quite a bit, and some discussion over the years about whether aftermarket glass fits has, to me been resolved by Carl Nelson's comment to the effect that the windshield is a structural element of the greenhouse of a coupe. Think about it: with very thin A and C pillars, no B pillar at all, the top of a coupe is real flexible, especially so without the glass to stiffen it.
Thus, when glass is removed, stiffness is lost and the body deforms from stresses previously borne by the glass. Result: new glass leaks, whistles, doesn't want to go in, and so on.
The result of flexibility and the above problems in fitting give aftermarket glass a bad rap that it may not deserve. Since so few of us will ever have the chance to line up a original windshield against any of several aftermarket products, we may never really resolve whether aftermarket glass deserves its reputation for poor dimensional quality.
Choose: if you have a BMW windshield and an aftermarket glass, which is better and more "true"? We hope the OE BMW glass will be, but what are the allowable tolerances? Maybe the aftermarket is actually closer to the designer's intention. All you can know is what happens after installation. Who would pull a newly installed BMW glass to replace it with aftermarket?
Soooooo...
1. I don't want to blame aftermarket glass for all the reported difficulties that others have experienced.
2. If I ever get a new windshield installed (quoted $750 at the dealer here) I will make sure the installer very well supports the car before removing the existing one. Just how this will be done remains to be seen.